Any music act with a sizeable following likely has a cult of devotees. Jimmy Buffet has Parrotheads. Phish has Phishheads. And then there’s the granddaddy of them all: The Deadheads.

Deadheads set the standard for loyalty and devotion that few other groups can rival. They affirmed the Dead as a ’60s phenomenon and ensured the band’s continuing populist appeal, turning their fan base into a broad-based community that developed its own language, rules and mores. And while both the fans and band members have aged and morphed into middle age, that devotion for the Dead has never, ever subsided.

Joanne Jaspen of Chicago rests in front of her car after the Grateful Dead’s concert at J.F.K. Stadium in Philadelphia on July 8, 1989. Hundreds of the band’s followers, known as Deadheads, used the parking lots as campgrounds before traveling to the band’s next concert. (AP Photo/Charles Krupa)

While the term “Deadheads” only seemed natural — it incorporated both the band’s abbreviated moniker and the label normally associated with the hippies and freaks that made up the band’s early audience — it was first applied as a rallying cry that appeared in print on the sleeve of the group’s second live album, known simply as “Grateful Dead” (also referred to as the Skull & Roses album). It read: “Dead Freaks Unite: Who are you? Where are you? How are you? Send us your name and address, and we’ll keep you informed. Deadheads, P.O. Box 1065, San Rafael, California, 94901.”

Critic Robert Christgau first made note of the phenomenon at a Grateful Dead concert in 1971, when he observed “how many regulars seemed to be in attendance, and how, from the way they compared notes, they’d obviously made a determined effort to see as many shows as possible.”

The resulting Deadheads newsletter had a slow start — garnering only around 350 letters by the end of 1971 — although ultimately the numbers swelled to as many as 40,000.

There were 25 newsletters posted between October 1971 and February 1980, after which it was succeeded by the Grateful Dead Almanac, before the mailings gave way to Dead.net. Meanwhile the band started to embrace their followers in other ways, as well.

Song selection would be altered from show to show to give variety to those who attended consecutive shows. Often, the band further altered the set list by playing two sets in a single concert. The set rotations encouraged Deadheads to follow the band on tour and see multiple shows, knowing there would be little chance for repetition. As a result, multiple concerts could be performed in a single venue and still be assured of a sell-out due to the influx of out-of-town travelers. At the same time, a community began to develop among these rabid followers — one spawned from the early acid tests that drew the Dead’s first followers in their formative years — and expanded into a cult following with a common bond that turned each gathering into an extended family reunion. Concerts evolved as spiritual experiences that took audiences to higher planes and elevated states of consciousness that eliminated the boundaries between the musicians and their masses. That relationship was documented in “Grateful Dead: The Official Book of The Deadheads,” which was first published in 1983 and remained in print for 26 years.

Guitarist Jerry Garcia wrote the foreword and he, the band and promoter Bill Graham were presented with copies backstage at the Berkeley Greek Theater following a run of three performances on May 15, 1983.

Of course, the Deadhead phenomenon was evident well before the term came into existence. In the late 1960s, the band had a faithful following that flocked to their shows whenever the band played in, around and near San Francisco. By the early ’70s, the Deadhead clans became a multi-generational gathering as younger siblings and new recruits joined the original followers. Some became entrepreneurs, selling tie-dyed T-shirts, snacks and, of course, contraband outside the concert venues as a means to fund their travel. Eventually, these impromptu marketplaces became known as “Shakedown Street,” a reference to the Dead album of the same name.

Mike Morin, a devoted Deadhead who became hooked on the band while in high school, was one such Deadhead. He estimates he’s been to some 75 shows since 1973.

“There were a bunch of us who would go on the road trips and chip in for everything,” Morin recalls. “Back in the early days, we would camp out, but in the later days, we did hotels or motels … It wasn’t as crazy in the ’70s as it became later; you could get tickets to all the Music Hall shows in Boston without that much trouble. The shows were marathons and just wonderful experiences. Then we started taking more road trips to see them, as well as to see the offshoot bands.”

Morin estimates that he’s attended Dead concerts in 10 states over the past 40 years. Dennis McNally, the band’s longtime publicist and later its biographer, remembers how the Deadhead phenomenon began to transition once the band emerged from the underground.

“In the ’80s, they were the last band standing as far as representing certain values, both musical and social,” McNally says. “When we did ‘Touch of Grey,’ my take was that the Deadheads were kind of proud that we had been embraced by the larger public. It generated an enormous amount of interest from people, who, up until that point, became Deadheads through an organic process. You met somebody who was a fan. You learned in a casual, but slow kind of way. And you learned some ethics and behaviors along with your interest in the band. In 1987, however, suddenly you have people who heard the record on the radio and said ‘Ah, that sounds interesting, I’ll go to the show.’ And then they find out they can’t get tickets, because the show’s sold out.

“So they go anyway, and they hang out, and they have this roaring party in the parking lot. And for the next eight years, until Jerry died, we had thousands of people without tickets at every show. And they didn’t have any manners. They didn’t know any better. They just saw a raging party. But it’s hard to tell a 19-year-old he can’t go to the party.”

At the same time, Deadhead merchants began expanding their wares to include live recordings of Dead concerts — not surprising since the Dead would often set aside areas of the audience to allow for taping. As time went on, the tapes were increasingly exchanged and widely circulated, becoming a vital element in the Dead community. While some bands shunned the idea of home recordings, the Dead didn’t seem to mind.

“When we are done with it, they can have it,” Jerry Garcia said famously. “There’s something to be said for being able to record an experience you’ve liked, or being able to obtain a recording of it … my responsibility to the notes is over after I’ve played them.”

While many of The Grateful Dead’s loyal followers were content to camp out in a parking lot, it’s nice to know that motels were available for just $12 at the time of this concert. Photo courtesy Arista Records/Rhino Entertainment.

The band had unconditional love for its fans, McNally insists.

“After all, they were our bread and butter. The band tried to protect them, and tried, in a big brother kind of way, to advise them when necessary,” he says.

As the ’80s progressed, the internal workings of the Deadhead ecosystem became more sophisticated in other ways, as well, with various factions spinning off into self-directed areas of responsibility.

“In the Darkers” — a reference to the “In The Dark” album and a single released in the late ’80s, also known as “Touchheads” — took on the role of advisers and overseers to help curb any disorder. That gave rise to the “Minglewood Town Council” — the name of which was taken from another of the Dead’s signature songs — which helped keep order in specific ways by encouraging people to clean up after themselves and take responsibility for their actions before, during and after a show.

“To that point, there had been a lot of camping, which is to say people were allowed to sleep in their cars,” McNally says. “However, when we played Giants Stadium, the management came to us and said, ‘If you do three shows here and there’s camping, we are going to have to provide city services for anywhere between 10,000 and 20,000 people for five days. We’re not set up for that.’ So we agreed to ban it. In 1988, we said there would be no more camping. We also agreed to no more vending. It was an attractive nuisance; in other words, it attracted a lot of people. So then we got people saying The Grateful Dead are selling out and cashing in by making people buy our T-shirts instead of the T-shirts that were being sold in the parking lot. But this was simply not so. The amount of money we made on merchandising wasn’t even large enough to be a part of our equation. We were just trying to manage the party in the parking lot. But chasing people for selling T-shirts or veggie sandwiches was tough. We got resentment on those issues, but what could we do? We had to book these venues, so we had to accommodate the management.”

Sadly, it seems that the Deadheads who followed in the ’90s were generally not as disciplined as their forebears. Many were young people from upper-income homes who could afford to live the vagabond existence with a certain degree of material comfort. The rules developed early on began to disintegrate, often leading to confrontations with the police. A gate-crashing incident led to a riot at the Deer Creek Music Center near Indianapolis in July 1995, with gatecrashers becoming so out of control that the concert had to be canceled.

“It was a marvelous venue,” McNally remembers. “But we made a huge mistake. We had always played there in the middle of the week, so the population wasn’t too large. But this show was scheduled for a long weekend, so it gave an excuse for these hordes of unruly people to come and cause a riot. The band was watching what was going down with the crowd and thinking, ‘This is our audience?’ That was truly shocking. We had to cancel the show the next day because the police said they wouldn’t put themselves in harm’s way. And without them, we wouldn’t risk compromising the security of our audience. That was the only time we canceled a show due to audience misbehavior.”

Grateful Dead fan Ray McDermott of Steamboat Springs, Colo., waits amid acres of tie-dye for customers in the parking lot of the Rosemont Horizon in Rosemont, Ill., on April 11, 1989. Such impromptu marketplaces became known as “Shakedown Street,” a reference to the Dead album of the same name. AP photo/Fred Jewell)

Although The Grateful Dead officially disbanded after Garcia’s death, the Deadheads still remain loyal to the band’s various spinoffs, and new cults of followers have spun off in their wake.

“Spinners” (also referred to as “The Family” or “Church of Unlimited Devotion”) were often seen at shows twirling in ecstasy and would later adapt the band’s music for their own spiritual sacraments.

“Wharf Rats” (another song reference) helped encourage the abstention of drugs and alcohol.

“Wookies,” or “Wooks,” were the fans who were the most unkempt and hard-bitten of the devotees who mastered the art of living on the road.

For the most part, however, the list of those who considered themselves Deadheads began leaning more and more toward professionals and even politicians — a far cry from the hippie hordes who initially embraced the band.

In fact, the names of those who consider themselves followers include some of the world’s major movers and shakers, including President Bill Clinton; British Prime Minister Tony Blair (who actually played in a Dead cover band while attending university); New Jersey Governor Jon Corzine; political commentator Tucker Carlson; the late journalist Walter Cronkite (he attended two Dead concerts and became a personal friend of drummer Mickey Hart); Al and Tipper Gore; U.S. Senator Patrick Leahy of Vermont; Apple founder Steve Jobs; comedienne Whoopi Goldberg; Speaker of the House Nancy Pelosi; U.S. Senator Al Franken of Minnesota; basketball star Bill Walton; singer and poet Henry Rollins; and novelist William Gibson.

“From my point of view, all the real fans were Deadheads,” McNally says. “You can make a point of how many shows you’ve seen, how much of your personal life you gave up to prepare for the next tour, etc., etc. That’s certainly a valid description. When I was starting out, the competition was not so much how many shows you’ve seen, but, when the band is tuning and getting ready to play the next song, how many notes will it take you to guess the next song? I can name that tune in four notes! I was a fierce competitor in that silliness. “But in general, the great thing about Deadheads was that there was a sense of inclusion. If you’re here, then you’re part of the family.”